1. Field of the Invention
The present invention relates to a composite wiring board in which at least two rigid wiring boards are joined and a manufacturing method thereof.
2. Description of the Related Art
Conventionally, a composite wiring board in which at least two rigid wiring boards are disposed substantially in parallel to each other and are joined to each other for attaining to be small in size and excellent in function has been used.
FIG. 1A is a side view showing a first example of the conventional composite wiring board.
The composite wiring board 10 has a structure that connectors 13, 14 are respectively mounted on two rigid wiring boards 11, 12 and a lead wire or a flexible wiring board 15 are inserted into each of the connectors 13, 14 to join each of the rigid wiring board 11, 12.
Because the connectors 13, 14 need to have a height and an area to a certain extent owing to the necessity of a pitch of a connector pin or other necessities, the composite wiring board 10 having the aforesaid structure has a fault that it is not suitable for high density mounting.
FIG. 1B is a side view showing a second example of the conventional composite wiring board.
The composite wiring board 20 has a structure that counterparts 23, 24 of a board-to-board connector capable of being divided into the two counterparts 23, 24 are mounted on two rigid wiring boards 21, 22, respectively, and that the counterparts 23, 24 of the board-to-board connector are fit to each other and thereby each of the rigid wiring boards 21, 22 is joined to each other.
The composite wiring board 20 having such a structure does not need any lead wires and thereby does not require any troubles of the connection of the two rigid wiring boards 21, 22. However, because the composite wiring board 20 has the structure formed by the simple pressing to each other of the counter parts 23, 24 of the board-to-board connector for joining them, the composite wiring board 20 has a disadvantage that the counterparts 23, 24 of the board-to-board connector are easy to come off owing to vibrations and other forces at the time of the usage thereof.
FIG. 1C is a side view showing a third example of the conventional composite wiring board.
The composite wiring board 30 has a structure that a lead wire or a flexible wiring board 33 is directly soldered on two rigid wiring boards 31, 32 for joining each of the rigid wiring boards 31, 32.
The composite wiring board 30 having such a structure becomes less expensive in costs because it does not have the aforesaid connectors 13, 14, 23 and 24, but it has a disadvantage that it is not suitable for high density mounting because It has a necessity of widening the pitches of the circuit patterns on the rigid wiring boards 31, 32 for preventing the bridging of solder.
FIG. 1D is a side view showing a fourth example of the conventional composite wiring board.
The composite wiring board 40 is a flex rigid wiring board that has a structure using two rigid wiring boards 41. 42 that put a flexible wiring board 43 at the center part of each of them.
Because the flexible wiring board 43 is put in each of the rigid wiring boards 41, 42 in the composite wiring board 40 having such a structure, the joining of each of the rigid wiring boards 41, 42 is strong. Moreover, because the decrease of the mounting area is not produced like in each of the aforesaid composite wiring boards 10, 20 and 30, the composite wiring board 40 is suitable for high-density mounting.
Because it is needed for the aforesaid fourth example of the conventional composite wiring board 40 to put and fix the flexible wiring board 43 having flexibility between the rigid wiring boards 41, 42, a specific adhesive is needed, and the gluing processes thereof are complicated, and further the coefficient of utilization of the material is also decreases. Consequently, the composite wiring board 40 has a disadvantage that it becomes very expensive. Moreover, because the composite wiring board 40 has a necessity to bend the flexible wiring board 43 between the rigid wiring boards 41 and 42, the composite wiring board 40 has another disadvantage that it needs a space for the bending.
Accordingly, an object of the present invention is to solve the aforementioned problems and to provide a composite wiring board that occupies a small space and is low in price and a manufacturing method thereof.
According to the present invention, the foregoing and other objects and advantages are attained by a composite wiring board comprising at least two rigid wiring boards on an end face of each of which a connection portion is formed, wherein each of the rigid wiring boards is arranged so that each of the connection portions is situated on a plane and each of the corresponding connection portions is connected with each other in the plane.
Because the connection portions are formed on the end faces of the rigid wiring boards according to the aforesaid structure of the invention, the plural rigid wiring boards can be Joined by the connection of each of the corresponding connection portions at the side face of each of the rigid wiring boards. Consequently, existing connection means can be applied to the connection of each of the connection portions, and thereby the composite wiring board can be manufactured inexpensively in cost. Moreover, because the connection means can be arranged in one plane, it is possible to attain the decrease of the space of the composite wiring board.
As described above, according to the invention, a composite wiring board that is inexpensive and occupies a small space can be provided.